This invention pertains to multipurpose food processors of the type including a base housing having a drive unit therein with a rotary tool spindle protruding vertically therefrom. A bowl is mounted on the base housing and has a bottom opening through which the spindle extends. Various tools may be mounted on the spindle for rotation within the bowl for processing different types of foods. A cover mounted on the bowl has an opening through which food may be introduced to be sliced, chopped, grated, mixed, pureed or otherwise prepared. Examples of food processors of this type will be found in U.S. Pat. Nos. 3,892,365 of Verdun and 3,985,304 of Sontheimer.
Most prior art food processors of the type referred to employ a squirrel cage induction motor as the main drive. The advantage of such a motor is that its speed is compatible with the operations to be performed and, accordingly, it requires no speed reduction. However, it is heavy and expensive. Also, its load characteristics are not particularly good as motor slip and tendency to overheat become relatively pronounced at higher loads. Furthermore, its vertical mounting means that the base housing must be relatively tall and this is a disadvantage when used and stored in the average home kitchen. It would be preferable to employ a universal motor in a device of this type as such motors are lightweight and inexpensive and have the added advantage of being operable on both AC and DC current. However, the speeds of these motors are quite high, on the order of 10,000-20,000 rpm. or more. This necessitates some type of gearing or belting. In prior art food processors employing universal motors, the universal motors have been mounted on a vertical axis and connected by belt to the vertical tool spindle. This has resulted in rather bulky base housings in order to provide room for pulleys, belts, etc.
Most prior art food processors are designed in such a manner that the cover must be securely clamped to the bowl before the drive unit will start. Removal of the cover automatically deenergizes the drive. This is a safety feature to prevent injury to the user by the often sharp, spinning tools. However, the blades will continue coasting for a time after the motor is deenergized, and this could result in injuries if the user suddenly removed the cover and immediately reached into the bowl.
Finally, it is also important to keep the vibration and noise of a home kitchen appliance to an absolute minimum. The motor mounting of many of the prior art processors leaves much to be desired in this regard.
Accordingly, it is a primary object of the present invention to provide an improved food processor wherein the drive unit employs a universal motor with a unique gearing arrangement resulting in an extremely compact and efficient power package.
Another object is to provide such a processor wherein the motor is mounted in a nearly vibration-free, yet simple and efficient manner.
Another object is to provide such a processor wherein the spinning tools are braked to a stop upon removal of the bowl cover.
Other objects, features, and advantages will become apparent from the following description and appended claims.